很多人都知道「am」代表上午
「pm」代表下午
可是中午或者午夜12點是「am」還是「pm」呢?
腦子是不是突然卡殼了?
和小編一起搞清楚如何表達吧
The 12-hour system divides the 24 hours of a day into two periods lasting 12 hours each. The first 12-hour period is designated as am. It runs from midnight to noon. The second period, marked pm, covers the 12 hours from noon to midnight.
12小時制將一天中的24小時分為兩個時段，每個時段都有12小時。第一個12小時時段指定為am（上午）：從午夜開始到中午。第二個時段標為pm（下午），從中午到午夜。
The abbreviations am and pm derive from Latin:
am和pm是從拉丁語縮寫來的
AM = Ante meridiem : Before noon
意思是在中午前
PM = Post meridiem : After noon
意思是在中午後
meridiem /mə'ridi:əm/ n.正午
Ante meridiem is commonly denoted as AM, am, a.m., or A.M.; post meridiem is usually abbreviated PM, pm, p.m., or P.M.
Ante meridiem通常會寫成AM, am, a.m., 或者是A.M.
post meridiem會縮寫為PM, pm, p.m., 或 P.M.
Like many other sources, timeanddate.com uses am and pm, but the other variants are equally correct and widely used.
大多數的時間書寫，就像世界日期及時間網一樣是使用am和pm的，但其他變體也同樣正確並被廣泛使用。
The main weakness of the 12-hour system is a widespread confusion about which abbreviation should be used for noon and midnight: neither moment can logically be identified as before noon (am) or after noon (pm). For example, the moment of midnight occurs precisely 12 hours after noon on the previous day and 12 hours before noon on the following day.
12小時制的主要缺點是人們普遍混淆了正午和午夜的縮寫：從邏輯上講，這兩個時刻都不能被定義為正午之前(am)或正午之後(pm)。例如，子夜的時刻發生在前一天中午12小時後，第二天中午12小時前。
However, most digital clocks and most sources, including timeanddate.com, designate midnight as 12 am and noon as 12 pm. Although the precise moment of noon falls in neither category, the hour succeeding it, from 12:00:01 to 12:59:59, is clearly after noon.
然而，大多數數字時鐘和大多數時間源，包括世界日期及時間網，都將午夜定為12 am，中午定為12 pm。雖然恰好中午的那個時間點好像哪個類別都並不屬於，但從12:00:01到12:59:59的連續時間顯然是在正午之後。
To avoid any confusion when referring to the precise moment of noon or midnight, we recommend using the designations 12 noon and 12 midnight instead.
為了避免在提到中午或午夜對準確時刻產生混淆，我們建議使用12 noon和12 midnight來代替。
中午或正午 (noon) 通常叫做
12:00 p.m.
子夜或午夜 (midnight) 叫做
12:00 a.m.
美國國家標準與技術研究所
(National Institute of Standards and Technology，NIST)
給出答案：
meridiem 就是 noon，
正午十二點應該表達為12:00 noon ，
而午夜十二點可以表達為12:00 midnight，
以方便區分。
不過，
12:00 midnight 的用法也比較模稜兩可，
因為它無法區分是某一天開始的午夜，
還是結束的午夜。
要想解決這個問題，
可以用00:00(zero o'clock)
來表示某一天開始的午夜。